Puerto Rican Amazon

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Puerto Rican Amazon

Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Aves
Order: Psittaciformes
Family: Psittacidae
Genus: Amazona
Species: A. vittata
Binomial name
Amazona vittata
Boddaert, 1783
Subspecies
  • A. v. vittata
  • A. v. gracilipes †

The Puerto Rican Amazon (Amazona vittata), also known as the Puerto Rican Parrot or Iguaca, is endemic to the archipelago of Puerto Rico belonging to the neotropical genus Amazona. Measuring 28–30 cm (11–12 in), the Puerto Rican Amazon is a predominantly green parrot with a red forehead and white rings around the eyes. Two subspecies have been described, although there are doubts over the distinctiveness of the form gracilipes from Culebra Island, extinct since 1912. Its closest relatives are believed to be the Jamaican Black-billed Amazon (Amazona agilis) and the Hispaniolan Amazon (Amazona ventralis).

Puerto Rican Amazons reach sexual maturity between three and four years of age. They reproduce once a year and are cavity nesters. Once the female lays eggs she will remain in the nest continuously incubating them until hatching. The chicks are fed by both parents and will leave the nest 60 to 65 days after hatching. This parrot's diet is varied and consists of flowers, fruits, leaves, bark and nectar obtained from the forest canopy.

The species is the only remaining native parrot in Puerto Rico and one of the ten most endangered bird species in the world. Initially widespread and abundant, the population declined drastically in the 19th and early 20th centuries with the removal of most of its native habitat, also vanishing from nearby Vieques Island and Mona Island. Conservation efforts were started in 1968 to save this species from likely extinction. In 2006, the total population was estimated between 34 and 40 individuals living in the wild with captive population of 143 parrots.[2]

Contents

[edit] Taxonomy and naming

The Puerto Rican Amazon was described by Dutch ornithologist Pieter Boddaert in 1783. It belongs to the large neotropical genus Amazona, commonly known as Amazons; these birds have also been given the generic epithet of 'parrot' by the American Ornithologists' Union, hence Puerto Rican Parrot is an alternative common name in North America.[3] The indigenous Taíno people called it the Iguaca, an onomatopoeic name that resembled the parrots' flight call.[4]

There are two recognized subspecies:

  • A. v. vittata is the nominate and only extant subspecies, inhabiting Puerto Rico and formerly nearby Vieques Island and Mona Island.[5]
  • A. v. gracilipes inhabited Culebra Island and is now extinct. It is unclear whether it was substantially different from the nominate subspecies vittata.

[edit] Evolutionary history

There is no of evidence that the West Indies were connected to a continent in the past, and thus the various native bird species are assumed to be descended from those that immigrated to the Caribbean at some point. Some small species would encounter problems traversing large bodies of water, but parrots have flight strength and various behavioral characteristics that would facilitate "over-water" dispersion.[6] Most Caribbean bird species originate from Central, North and South America.[7] The Amazona species found in the Caribbean are divided in two groups: five mid-sized species found in the Greater Antilles and seven large species in the Lesser Antilles.[8] All the Greater Antillean Amazons display closely-related characteristics, including predominantly green-toned color patterns and white rings around the eyes.[8] David Lack considered that the Puerto Rican Amazon was derived from the Hispaniolan Amazon (A. ventralis) found in Hispaniola, but it has been argued that Lack omitted some elements in his analysis, including the similarities found between the Black-billed Amazon (A. agilis) of Jamaica and the Puerto Rican Amazon.[9] Subsequent studies showed that size and color patterns were not definitive, finding that pattern changed with relative ease even within members of the same species.[9] The research concluded that the Puerto Rican Amazon may share a common ancestor with the Jamaican A. agilis.[10]

[edit] Description

The Puerto Rican Amazon measures 28–30 cm (11–12 in) and weighs from 250–300 g (9–10.5 oz) with an average of 275 g (10 oz). Although small compared with other Amazons, it is similar in size to other Amazona species of the Greater Antilles. Sexual dimorphism is not present; both the male and female bird have predominantly green plumage with paler and yellow-tinged underparts, a red forehead and white ovals around the eyes. The iris is brown, the bill a horn color and the legs yellow-tan. The wing primaries and main coverts are dark blue.[11] The green feathers have blue edges. The color of the feathers on the bird's underside vary depending on the bodypart where they are located. Those found on the wings' underside, which can be seen during flight, are bright blue while those in the tail exhibit a yellow-green tone. Aside from DNA-sexing, males and females can only be distinguished by behavioral differences during the breeding season. Immature birds have similar plumage to adults.[11]

[edit] Population and distribution

The precise distribution of the Puerto Rican Amazon before the arrival of Spanish colonialists is unknown due to lack of contemporary records and the disappearance of the indigenous Taíno people,[12] but the species was known to be widespread and abundant, with Edward Cavendish Taylor, a British ornithologist reporting in 1864 that the parrots were common near San Juan.[13]

There is evidence the species may have also inhabited Antigua, Barbuda[14] and the Virgin Islands.[15][16] During the latter half of the 19th century, most of Puerto Rico's virgin forests, historical habitat of the species, were cleared for agricultural development, primarily the production of sugar, cotton, corn and rice. With this development, the Amazon quickly became reliant on these crops as their main food source and became known as pests; the local farmers repelled or hunted the birds if possible.[17] As the agricultural work expanded, the number of parrots declined and their habitat continued to be reduced. Before this, humans had not been a significant threat to the species; the Taíno were known to hunt the parrot but this did not have a significant effect in their population.[18] Accounts recorded in the early 1900s place the parrots traveling away from the Luquillo forest and the Sierra de Cayey towards the main island's coast in order to find food sources.[12] Within this timeframe, the species was extirpated from Puerto Rico's smaller islands—Culebra (1912), Vieques and Mona—and became restricted to five locations: two in karst-limestone areas, two in high montane rain forests and one in mangrove forest at the foot of the Caribbean National Forest (now the El Yunque National Forest). One of these karst regions, located in the northwestern part of Puerto Rico, was identified as a haven for the species, particularly a region named Valle de las Cotorras (Valley of the Parrots) located between San Sebastián and Morovis, where there was a sizable population. Some Amazons survived in small pockets of degraded forest but these proved insufficient for the subsistence of large colonies, eventually limiting their natural habitat to the Cordillera Central and undisturbed forest areas. By 1940, the species was restricted to primary forest at the Luquillo Mountains in the Caribbean National Forest.

The species historically occurred in eight mature or old-growth forests in Puerto Rico at all elevations, in holes, in cliffs, and other diverse habitats at lower elevations. The species could be found at medium elevations at the Guajataca State Forest until 1910 and in the Rio Abajo State Forest until the 1920s and at high elevations in the Carite State Forest until the 1930s.[19] The present elevation for the species is between 396 and 823 m (1,300 and 2,700 ft). Since the species needs mature forests with open-cavity trees for reproduction, it does not occur in dwarf and second growth forests. The current range of the species is 16 km² (6 sq. mi), 0.2% of its former range.[1]

Early estimates of the parrot's numbers vary greatly, with some authorities claiming more than one million individuals,[20] while others propose a more modest population of 100,000. During the first 150 years of Spanish rule the human population was small, and in 1650, when the population of the island was 880 people, the species was still abundant throughout the archipelago.[21] After 1650 the human population increased exponentially, and the Puerto Rican Parrot population started to decline. Outside of agricultural development, several factors contributed to the decrease in numbers, including the construction of roads, hydroelectric development, and the adoption of young chicks as pets.[22] Heinrich Moritz Gaede, a German naturalist, declared that by 1836 the parrot population had noticeably declined.[13] In the 1950s, the wild population declined to 200 individuals. This trend continued, reaching an absolute low of 13 individuals lining in the wild in 1975. A short-lived recovery followed and in August 1989 the population was estimated at a minimum of 47 individuals, but on September 18, 1989, Hurricane Hugo struck the northeast coast of Puerto Rico inflicting heavy casualties on the remaining individuals. In the aftermath of the hurricane the population was estimated at 23 individuals and presently, the wild population is estimated between 34 and 40 individuals.[23][2]

[edit] Behavior

The Puerto Rican Amazon is diurnal, typically beginning its day half an hour after sunrise.[24] It is generally secretive when inside its nest, using its green plumage as camouflage. In contrast, the bird may be vocal and noisy when exiting the nest. Upon taking flight, its color pattern provides some contrast to the forest. The flight mechanism involves strokes below the body axis, unlike most birds whose wings flow above their bodies in flight. Amazons can fly moderately fast, reaching a top speed of approximately 30 km/h (18 mph), and are fairly agile when evading predators in mid-air.[25] When in search of food, the parrot groups in pairs. Couples and their fledged young display a tendency to stay together.[26] The Amazon makes two flight calls, a take-off squawk which consist of a pattern of long squawks, and a loud "bugle", commonly used in flight and which may have several meanings depending on the circumstance it is used.[27]

[edit] Diet

Like almost all amazons, the Puerto Rican Amazon is a herbivore. Its diet consists of flowers, fruits, leaves, bark and nectar obtained from the forest's canopy. The species has been recorded to consume more than 60 different materials, although its diet was historically more varied due to its larger range. Among the items it presently consumes are the pericarp of the seeds of sierra palm (Prestoea montana), tabonuco (Dacryodes excelsa), and negra lora (Matayba domingensis); the fruits of bejuco de rana (Marcgravia sintenisii), camasey (Miconia sintenisii), cupey de altura (Clusia gundlachii), and palo de cruz (Rheedia portoricensis); the flowers of bejuco de rana, achiotillo (Alchornea latifolia), and Piptocarpha tetrantha; the leaves and twigs of cupeillo (Clusia grisebachiana), laurel sabino (Magnolia splendens), caimitillo verde (Micropholis garciniaefolia), and Piptocarpha tetrantha; the bark of bejuco de rana, cupeillo, and cachimbo cumun (Psychotria berteriana); and the buds of cuaba (Inga vera).[28] They normally select the fruits positioned near "eye-level", picking them one at a time with some rare exceptions.[29] When feeding they use a foot to maintain balance on the perch where they stand while holding the food with the other.[30] The Amazon feeds in a slow, paused manner taking 8–60 seconds to consume separate items.[31]

[edit] Breeding

The Puerto Rican Amazon usually mates for life, with pairs only changing mates if one bird perishes or abandons the nest.[32] A male may abandon the female if the latter is injured, re-mating with a more "physically perfect" subject.[32] The pairing process is unknown; however, new pairs tend to participate in mutual "bowing displays" consisting of partial extension of the wings and full tail expansion.[33]

The Puerto Rican Amazon is a secondary cavity nester, nesting in tree trunk cavities: either in naturally-occurring cavities, or those excavated by other species. They prefer to nest in Palo colorado trees (Cyrilla racemiflora), but use other trees, including the laurel sabino (Magnolia splendens) and tabonuco (Dacryodes excelsa), to a lesser extent. These trees are mature cavity-forming trees which provide protection against predators and the entry of water. Recently, the species has also nested in artificial wooden boxes designed as part of the recovery plan for the species. Nest height varies from 7–15 m (23–50 ft) above ground. The male usually leads the search for nest sites, although the final decision seems to be taken by female.[34] Once a site is selected, the pair will spend some time inspecting and cleaning it. No lining material is added to the nest.

Puerto Rican Amazons reach sexual maturity at 4 years of age in the wild and at 3 years in captivity. The species usually reproduces once a year during the dry season, between the months of January and July. Copulation between pairs seems to be closely-related to food-transfers, with this possibly serving as a trigger for intercourse.[35] Amazons have a copulation pattern similar to that found in other parrots throughout the Americas, with the male gripping a perch with one leg while passively placing the other in the female's back.[36] As the time for egg-laying approaches the pair spends more time in the nest, with the male providing food to the female via regurgitation.[37] The female lays 2–4 eggs that she exclusively incubates for a period of 24 to 28 days, while the male will be present in the vicinity of the nest when providing food.[38] Females rarely leave the nest, leaving it on rare occasions involving repelling predators or if the male has nott brought food in a extended time frame.[39] The chicks are fed by both parents until they leave the nest around 60 to 65 days after they hatch.[2] Nonetheless, they remain dependent on their parents and travel with them until the next breeding season.[3]

Like other Amazons, the Puerto Rican Amazon is gregarious, and territorial around its nest.[40] The size of the territory around the nest averages 50 meters (164 feet).[5] Pairs are extremely cautious near their nest, usually moving in a slow manner when leaving the nest to avoid the attention of predators.[41] Although territorial defense is mostly composed of loud vocalizations there are instances of actual physical combat.[42] Pairs will defend their nest sites against invading couples, sometimes focusing on the location's defense instead of egg-laying. Pairs nesting in areas uninhabited by other parrots will remain mostly silent unless other parrots enter the zone.[42] Some pairs may display moderate territoriality even when not presenting intentions to nest, with these tendencies beginning in the latter half of the breeding season. It has been estimated that this may be observed in young pairs that had still not reached full maturity, serving as "practice territoriality".[43]

[edit] Threats and conservation efforts

The Puerto Rican Amazon is one of the ten most endangered bird species in the world. It entered the United States Endangered Species list on March 11, 1967. At the time of inclusion the population was estimated at 70 individuals. In 1968, recovery efforts began to increase the population in the wild.[44] In 1972, when the estimated population was 16 individuals, the United States Fish and Wildlife Service at the Luquillo Aviary began efforts to breed parrots in captivity. Conservation efforts have paid off remarkably. In June 2006, it was reported by the USFWS that its birds in captivity had successfully hatched 39 chicks (the yearly average is around 16). The total wild population is currently estimated between 34-40 individuals.

[edit] Threats

Red-tailed Hawk (B. j. jamaicensis), known as Guaraguao in Puerto Rico, a natural predator of the Puerto Rican Amazon.
Red-tailed Hawk (B. j. jamaicensis), known as Guaraguao in Puerto Rico, a natural predator of the Puerto Rican Amazon.

Arguably the main reason for the population decline of the Puerto Rican Amazon is man.[20] Early settlers of Puerto Rico, such as the Taíno, hunted it for food consumption but managed to maintain a healthy ecological balance. More recently, habitat destruction, capture of immature individuals for the pet industry, hunting, and predation have contributed to the sharp population decline. It is believed that the main reason for the decline of population is the clearing of mature forests for agricultural development.

Natural predators of the Puerto Rican Amazon include the Red-tailed Hawk (Buteo jamaicensis), the Broad-winged Hawk (Buteo platypterus), the Peregrine Falcon (Falco peregrinus) and the Pearly-eyed Thrasher (Margarops fuscatus).[2] The thrasher invaded Puerto Rico in the mid-20th century and become a problem for the parrots since 1973; to combat this, specially designed deep nests were prepared for the parrots in subsequent years to prevent competition from the invaders.[45]

Competition from introduced honeybees (Apis mellifera) and the related Hispaniolan Amazon (Amazona ventralis) for nesting cavities also represent a threat to the species. Introduced Black rats (Rattus rattus) and Indian mongooses (Herpestes javanicus) may eat eggs and chicks and may also compete for nesting cavities.[23]

Natural disasters, such as hurricanes, were not historically a threat to the Puerto Rican Parrot population, but as a result of the fragmentation and reduction of the population these disasters are now a threat to the species. In September 1989 Hurricane Hugo passed through the species's current range and reduced the population from 47 to 23 individuals.[46]

[edit] Recovery plan

Due to the low population and endangered status of the Puerto Rican Amazon, a recovery plan was drafted and implemented in 1968. Its main objective was to downlist the species to threatened status by the year 2020.[20] Other objectives included the establishment of two separate viable wild populations (consisting of a stable number of 500 or more individuals for a period of at least five years), the protection of habitat for those populations and the control of predators, parasites and competitors of the species.

A captive population was established in the Luquillo Aviary in 1973, as part of the conservation efforts.[20] Another was established in 1993 when some individuals where transferred from the Luquillo Aviary to the Rio Abajo State Forest under the administration of the Puerto Rican Department of Natural Resources (Departamento de Recursos Naturales y Ambientales).[47]

[edit] See also

Puerto Rico Portal
Birds Portal

[edit] References

[edit] Footnotes

  1. ^ a b BirdLife International (2006). Amazona vittata. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 2006-05-11. Database entry includes a brief justification of why this species is critically endangered and the criteria. used
  2. ^ a b c d Puerto Rican Parrots - Questions and Answers. U.S. Fish and Wildlife Service. Retrieved on 2008-06-04.
  3. ^ a b Puerto Rican Parrot (Amazona vittata). National Audubon Society. Retrieved on June 8, 2006.
  4. ^ Captive-bred Puerto Rican Parrots released in El Yunque. U.S. Fish and Wildlife Service (June 28, 2000). Retrieved on 2008-06-02.
  5. ^ a b Conservation Management Institute - Puerto Rican Parrot. Retrieved on March 9, 2008.
  6. ^ Snyder, et al., p.42
  7. ^ Snyder, et al., p.44
  8. ^ a b Snyder, et al., p.46
  9. ^ a b Snyder, et al., p.47
  10. ^ Snyder, et al., p.52
  11. ^ a b Forshaw, (Parrots of the World) p. 538
  12. ^ a b Snyder, et al., p.15
  13. ^ a b Snyder, et al., p.16
  14. ^ Charles A. Woods and Florence E. Sergile. Biogeography of the West Indies: Patterns and Perspectives. CRC, 183. ISBN 0-8493200-1-1. 
  15. ^ Oberle, Mark (2003). Las aves de Puerto Rico en fotografías (in Spanish). Editorial Humanitas. ISBN 0-9650104-2-2. 
  16. ^ Snyder, et al., p.18–19
  17. ^ Snyder, et al., p.22
  18. ^ Snyder, et al., p.21
  19. ^ Puerto Rican Parrot (Amazona vittata) - Species account. U.S. Fish and Wildlife Service. Retrieved on 2008-06-04.
  20. ^ a b c d Technical/Agency Draft Revised Recovery Plan for the Puerto Rican Parrot (Amazona vittata). U.S. Fish and Wildlife Service (April 1999). Retrieved on June 7, 2006.
  21. ^ Snyder, et al., p. 21–22
  22. ^ Snyder, et al., p.29–36
  23. ^ a b Puerto Rican Parrot - BirdLife Species Factsheet. BirdLife International. Retrieved on September 20, 2007.
  24. ^ Snyder, et al., p. 71
  25. ^ Snyder, et al., p. 67
  26. ^ Snyder, et al., p. 68
  27. ^ Snyder, et al., p. 70
  28. ^ Snyder, et al., p. 81–83
  29. ^ Snyder, et al., p. 79
  30. ^ Snyder, et al., p.81
  31. ^ Snyder, et al., p. 82
  32. ^ a b Snyder, et al., p. 131
  33. ^ Snyder, et al., p. 132
  34. ^ Snyder, et al., p. 141
  35. ^ Snyder, et al., p. 149
  36. ^ Snyder, et al., p. 150
  37. ^ Snyder, et al., p. 148
  38. ^ Snyder, et al., p. 155
  39. ^ Snyder, et al., p. 156
  40. ^ Forshaw, (Parrots of the World) p. 541
  41. ^ Snyder, et al., p. 157
  42. ^ a b Snyder, et al., p. 136
  43. ^ Snyder, et al., p. 139
  44. ^ Snyder, et al., p. 225
  45. ^ Forshaw, (Parrots of the World) p. 540
  46. ^ Hurricane Effects on Wildlife and Ecosystems. U.S. Geological Survey (1998-12-08). Retrieved on 2008-05-18.
  47. ^ Thomas H. White, Jr. and Fernando Nuñez-Garcia. From Cage to Rainforest. U.S. Fish and Wildlife Service. Retrieved on 2008-06-04.

[edit] Bibliography

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